The link doesn't work for the article, unless you subscribe.We know that species are going extinct every day, far beyond what would be a "normal" rate, from human activity. Some may be pollution absorbers.The biosphere has recovered from loss of biodiversity caused by various ELEs of various percentages of species. Just how many are actually necessary for humans to keep on depends on each individual species' place in the ecology of human survival. Some existing species are certainly antagonistic, while others are needed in the food chain.

_________________"With every decision, think seven generations ahead of the consequences of your actions" Ute rule of life.“We do not inherit the earth from our ancestors; we borrow it from our children”― Chief Seattle“Those Who Have the Privilege to Know Have the Duty to Act”…Albert Einstein